Terence Crutcher moments before he was tasered and then shot dead by police officer Betty Shelby.Tulsa police department

Lawyers acting for the family of Terence Crutcher, the black pastor fatally shot by a white police officer in Tulsa, Oklahoma, have said he posed no imminent threat despite claims by police that he was reaching into his vehicle.

The shooting of Crutcher by Officer Betty Shelby after his SUV broke down on Friday, was the latest in a series of fatal shootings that have raised questions of racial bias in US policing.

Two police videos of the Tulsa shooting that have been broadcast widely since their release on Monday have stoked the debate, with Democratic presidential nominee Hillary Clinton calling the contents "unbearable."

A lawyer for Shelby has said she acted because she feared for her life, believing Crutcher was reaching into his vehicle for a weapon.

Tulsa police have said that he was unarmed, there was no weapon in the vehicle, and released the videos showing he had his hands in clear view before he was shot.

Shelby has been placed on administrative leave and is under criminal investigation, prosecutors and police said. The US Justice Department has launched a separate, civil rights investigation about the use of force by officers.

At a news conference in front of the Tulsa County courthouse, lawyers for Crutcher's family released enlarged still images from the police videos they said showed the vehicle's window was closed and stained with blood after Crutcher was shot.

"He is not threatening to anyone," lawyer Benjamin Crump said. "How can he be reaching into the car if the window is up and there is blood on the glass?"

Crutcher's family called the shooting a criminal act and is seeking charges.

About 200 people gathered for a peaceful protest in front of Tulsa's Civic Center Plaza on Tuesday night, holding signs reading: "Justice 4 Crutch" and calling for Shelby to be arrested.

Scott Wood, a lawyer for Shelby, told the Tulsa World that Crutcher ignored repeated commands from the officer.

"He has his hands up and is facing the car and looks at Shelby, and his left hand goes through the car window, and that's when she fired her shot," said Wood.

Police said they received two calls of a car being broken down and blocking a road.

In one video shot from a police helicopter, a person is heard saying Crutcher is not following police instructions.

A voice from the helicopter then says: "That looks like a bad dude too, could be on something." An officer is seen with a weapon drawn before Crutcher drops to the ground, and a female officer can be heard on police radio saying: "Shots fired."

The video shows Crutcher on his back with what appears to be blood oozing from his torso.

A separate police dashcam video also shows the officer with a weapon drawn and following Crutcher as he walks to his vehicle with his hands in the air. A pop is heard as he appears to place his hands on the vehicle and he falls a few seconds later.

Crutcher's twin sister, Tiffany, said her brother was a church-going man who had enrolled at Tulsa Community College to better his life.

"That big 'bad dude,' his life mattered," she told a separate news conference on Monday.

Separately, protesters blocked a highway and clashed with police in Charlotte, North Carolina, early on Wednesday morning after officers fatally shot a black man they said had a gun when they approached him in a parking lot.

About a dozen officers and several protesters suffered non-life threatening injuries during an hours-long demonstration near where Keith Lamont Scott, 43, was shot by a policeman on Tuesday afternoon, police and local media said on social media.